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  • 1.
    Liu, Jian-li
    et al.
    University of Science and Technology Beijing, Beijing, China.
    Yao, Jun
    China University of Geosciences (Beijing), China.
    Wang, Fei
    University of Science and Technology Beijing, Beijing, China.
    Min, Ning
    China University of Geosciences (Beijing), China.
    Gu, Ji-hai
    China University of Geosciences (Beijing), China.
    Li, Zi-fu
    University of Science and Technology Beijing, Beijing, China.
    Sunahara, Geoffrey
    China University of Geosciences (Beijing), China; McGill University, Montreal, Quebec,Canada.
    Duran, Robert
    China University of Geosciences (Beijing), China; Université de Pau et des Pays de l’Adour, Pau Cedex, France.
    Solevic-Knudsen, Tatjana
    University of Belgrade, Belgrade, Serbia.
    Hudson-Edwards, Karen A.
    University of Exeter, Penryn, Cornwall, UK.
    Alakangas, Lena
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Bacterial diversity in typical abandoned multi-contaminated nonferrous metal(loid) tailings during natural attenuation2019In: Environmental Pollution, ISSN 0269-7491, E-ISSN 1873-6424, Vol. 274, p. 98-107Article in journal (Refereed)
    Abstract [en]

    Abandoned nonferrous metal(loid) tailings sites are anthropogenic, and represent unique and extreme ecological niches for microbial communities. Tailings contain elevated and toxic content of metal(loid)s that had negative effects on local human health and regional ecosystems. Microbial communities in these typical tailings undergoing natural attenuation are often very poorly examined. The diversity and inferred functions of bacterial communities were examined at seven nonferrous metal(loid) tailings sites in Guangxi (China), which were abandoned between 3 and 31 years ago. The acidity of the tailings sites rose over 31 years of site inactivity. Desulfurivibrio, which were always coupled with sulfur/sulfide oxidation to dissimilate the reduction of nitrate/nitrite, were specific in tailings with 3 years abandonment. However, genus beneficial to plant growth (Rhizobium), and iron/sulfur-oxidizing bacteria and metal(loid)-related genera (Acidiferrobacter and Acidithiobacillus) were specific within tailings abandoned for 23 years or more. The increased abundance of acid-generating iron/sulfur-oxidizing and metal(loid)-related bacteria and specific bacterial communities during the natural attenuation could provide new insights for understanding microbial ecosystem functioning in mine tailings. OTUs related to Sulfuriferula, Bacillus, Sulfurifustis, Gaiella, and Thiobacillus genera were the main contributors differentiating the bacterial communities between the different tailing sites. Multiple correlation analyses between bacterial communities and geochemical parameters indicated that pH, TOC, TN, As, Pb, and Cu were the main drivers influencing the bacterial community structures. PICRUSt functional exploration revealed that the main functions were related to DNA repair and recombination, important functions for bacterial adaptation to cope with the multi-contamination of tailings. Such information provides new insights to guide future metagenomic studies for the identification of key functions beyond metal-transformation/resistance. As well, our results offers novel outlooks for the management of bacterial communities during natural attenuation of multi-contaminated nonferrous metal(loid) tailings sites. 

  • 2.
    Kaasalainen, Hanna
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering. Sweco Environment, Luleå, Sweden.
    Lundberg, Paula
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Aiglsperger, Thomas
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Alakangas, Lena
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Impact of declining oxygen conditions on metal(loid) release from partially oxidized waste rock2019In: Article in journal (Refereed)
    Abstract [en]

    The best available technology for preventing the formation of acid drainage water from the sulfidic waste rock at mine closure aims to limit the oxygen access to the waste. There is, however, a concern that contaminants associated with secondary minerals become remobilized due to changing environmental conditions. Metal(loid) mobility from partially oxidized sulfidic waste rock under declining and limited oxygen conditions was studied in unsaturated column experiments. The concentrations of sulfate and metal(loid)s peaked coincidently with declining oxygen conditions from 100 to < 5 sat-% and to a lesser extent following a further decrease in the oxygen level during the experiment. However, the peak concentrations only lasted for a short time and were lower or in the similar concentration range as in the leachate from a reference column leached under atmospheric conditions. Despite the acid pH (~ 3), the overall quality of the leachate formed under limited oxygen conditions clearly improved compared with atmospheric conditions. In particular, the release of As was two orders of magnitude lower, while cationic metals such as Fe, Cu, Mn, and Zn also decreased, although to a lesser extent. Decreased sulfide oxidation is considered the primary reason for the improved water quality under limited oxygen conditions. Another reason may be the immobility of Fe with the incorporation of metal(loid)s in Fe(III) minerals, in contrast to the expected mobilization of Fe. The peaking metal(loid) concentrations are probably due to remobilization from solid Fe(III)-sulfate phases, while the relatively high concentrations of Al, Mn, and Zn under limited oxygen conditions were due to release from the adsorbed/exchangeable fraction. Despite the peaking metal(loid) concentrations during declining oxygen conditions, it is clear that the primary remediation goal is to prevent further sulfide oxidation.

  • 3.
    Nyström, Elsa
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Kaasalainen, Hanna
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Alakangas, Lena
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Suitability study of secondary raw materials for prevention of acid rock drainage generation from waste rock2019In: Journal of Cleaner Production, ISSN 0959-6526, E-ISSN 1879-1786, Vol. 232, p. 575-586Article in journal (Refereed)
    Abstract [en]

    Prevention and mitigation of acid rock drainage (ARD) from mine wastes are crucial for limiting environmental impact. However, preventive measures are often too expensive, potentially harmful to the environment or not applied early enough. This study aimed to test the potential of different secondary raw materials for maintaining a circumneutral pH (6–7) in a sulfide oxidation environment, allowing secondary minerals to form on reactive sulfide surfaces to prevent release of acid, metals and metalloids, and thereby ARD generation. Five materials (blast furnace slag, granulated blast furnace slag, cement kiln dust, bark ash, lime kiln dust) were selected based on their alkaline properties, availability and yearly yield. High sulfidic (>50 wt%, sulfide) waste rock from an active Cu–Zn–Au–Ag open pit mine in northern Sweden was leached in small-scale laboratory test cells under ambient condition for 4–8 weeks before adding secondary raw materials on the surface in an attempt to prevent ARD generation. During 52 subsequent weeks of leaching, the pH and electrical conductivity in the leachate from the waste rock varied between 1.7-4.6 and 2.1–22.8 mS/cm, respectively. All secondary raw materials were able to increase the pH to circumneutral. However, blast furnace slag, granulated blast furnace slag and cement kiln dust were not able to maintain a circumneutral pH for an extended time due to self-cementation or carbonation, whereas bark ash (1 wt%) and lime kiln dust (5 wt%) prevented acidity, metal and metalloid leaching. Materials such as cement kiln dust and bark ash contained elevated concentrations of, e.g., Cd and Zn, but the release of metals and metalloids was generally low for most elements, except for Cl, K and Na, most likely due to salt dissolution.

  • 4.
    Liu, Jian-li
    et al.
    School of Energy and Environment Engineering, University of Science and Technology Beijing.
    Yao, Jun
    School of Water Resource and Environment Engineering, China University of Geosciences, Beijing.
    Wang, Fei
    School of Energy and Environment Engineering, University of Science and Technology Beijing, Beijing.
    Ni, Wen
    School of Civil and Resource Engineering, University of Science and Technology Beijing.
    Liu, Xing-yu
    National Engineering Laboratory of Biohydrometallurgy, General Research. Institute for Nonferrous Metals .
    Sunahara, Geoffrey
    Department of Natural Resource Sciences, McGill University, Montreal, Quebec.
    Duran, Robert
    Equipe Environnement et Microbiologie, MELODY group, Université de Pau et des Pays de l’Adour, IPREM UMR CNRS.
    Jordan, Gyozo
    Department of Applied Chemistry, Szent István University.
    Hudson-Edwards, Karen A.
    Environment & Sustainability Institute and Camborne School of Mines, University of Exeter.
    Alakangas, Lena
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Solevic-Knudsen, Tatjana
    Institute of Chemistry, Technology and Metallurgy, University of Belgrade.
    Zhu, Xiao-zhe
    School of Energy and Environment Engineering, University of Science and Technology Beijing.
    Zhang, Yi-yue
    School of Energy and Environment Engineering, University of Science and Technology Beijing.
    Li, Zi-fu
    School of Energy and Environment Engineering, University of Science and Technology Beijing.
    China's most typical nonferrous organic-metal facilities own specific microbial communities2018In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 8, no 1, article id 12570Article in journal (Refereed)
    Abstract [en]

    The diversity and function of microorganisms have yet to be explored at non-ferrous metal mining facilities (NMMFs), which are the world's largest and potentially most toxic sources of co-existing metal(loid)s and flotation reagents (FRs). The diversity and inferred functions of different bacterial communities inhabiting two types of sites (active and abandoned) in Guangxi province (China) were investigated for the first time. Here we show that the structure and diversity of bacteria correlated with the types of mine sites, metal(loid)s, and FRs concentrations; and best correlated with the combination of pH, Cu, Pb, and Mn. Combined microbial coenobium may play a pivotal role in NMMFs microbial life. Arenimonas, specific in active mine sites and an acidophilic bacterium, carries functions able to cope with the extreme conditions, whereas Latescibacteria specific in abandoned sites can degrade organics. Such a bacterial consortium provides new insights to develop cost-effective remediation strategies of co-contaminated sites that currently remain intractable for bioremediation.

  • 5.
    Karlsson, Teemu
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering. Industrial Environments and Recycling Unit, Geological Survey of Finland, Kuopio, Finland.
    Räisänen, Marja Liisa
    Industrial Environments and Recycling Unit, Geological Survey of Finland, Kuopio, Finland.
    Lehtonen, Marja
    Mineral Processing and Materials Research Unit, Geological Survey of Finland, Espoo, Finland.
    Alakangas, Lena
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Comparison of static and mineralogical ARD prediction methods in the Nordic environment2018In: Environmental Monitoring & Assessment, ISSN 0167-6369, E-ISSN 1573-2959, Vol. 190, no 12, article id 719Article in journal (Refereed)
    Abstract [en]

    Acid rock drainage (ARD) is a major problem related to the management of mining wastes, especially concerning deposits containing sulphide minerals. Commonly used tests for ARD prediction include acid–base accounting (ABA) tests and the net acid generation (NAG) test. Since drainage quality largely depends on the ratio and quality of acid-producing and neutralising minerals, mineralogical calculations could also be used for ARD prediction. In this study, several Finnish waste rock sites were investigated and the performance of different static ARD test methods was evaluated and compared. At the target mine sites, pyrrhotite was the main mineral contributing to acid production (AP). Silicate minerals were the main contributors to the neutralisation potential (NP) at 60% of the investigated mine sites. Since silicate minerals appear to have a significant role in ARD generation at Finnish mine waste sites, the behaviour of these minerals should be more thoroughly investigated, especially in relation to the acid produced by pyrrhotite oxidation. In general, the NP of silicate minerals appears to be underestimated by laboratory measurements. For example, in the NAG test, the slower-reacting NP-contributing minerals might require a longer time to react than is specified in the currently used method. The results suggest that ARD prediction based on SEM mineralogical calculations is at least as accurate as the commonly used static laboratory methods.

  • 6.
    Hällström, Lina
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Alakangas, Lena
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Martinsson, Olof
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Geochemical characterization of W, Cu and F skarn tailings at Yxsjöberg, Sweden2018In: Journal of Geochemical Exploration, ISSN 0375-6742, E-ISSN 1879-1689, Vol. 194, p. 266-279Article in journal (Refereed)
    Abstract [en]

    Little attention has been paid to tailings from skarn ore deposits and their environmental impact, even though they can contain elevated concentrations of elements of potential concern together with sulfides and fluorite. Historical skarn tailings at Yxsjöberg, Sweden, containing e.g. Be, Bi, Cu, F, Sn, S, W, and Zn were geochemically characterized as a first step to evaluate the environmental impact and the potential to re-mine the tailings. The tailings were deposited between 1897 and 1963 in the Smaltjärnen Repository without dams or a complete cover, and have been in contact with the atmosphere for >30 years. Four vertical cores throughout the tailings were taken and divided into 134 subsamples, which were analyzed for total concentrations and paste pH. Selected samples from different depths were mineralogically characterized using optical microscopy, scanning electron microscopy (SEM) with energy dispersive X-ray spectroscopy (EDS), Raman vibrational spectroscopy, and X-ray diffraction (XRD). Minerals, hand-picked from drilled rock cores, were analyzed for the element content, and a modified Element to Mineral Conversion (EMC) that pinpoints the quantitative distribution of elements between the minerals in the tailings was carried out. The average concentrations of Be, Bi, Cu, Sn, Zn, W, F and S in the tailings were 284, 495, 946, 559, 301, and 960 ppm, and 1.9 and 1.2 wt%, respectively. The tailings has reached a late stage development due to pyrrhotite oxidation resulting in low pH (<4) in the uppermost tailings, and formations of secondary minerals such as gypsum, hydrous ferric oxides (HFO) and orthogonal calcite. Secondary pyrite and magnetite, formed from monoclinic pyrrhotite was detected, and different weathering rates of secondary pyrite, hexagonal and monoclinic pyrrhotite was indicated, with secondary pyrite as the most stable and monoclinic pyrrhotite as the least. The rare and easily-weathered mineral danalite (Fe4Be3(SiO4)3S) was found in the drilled rock cores and by XRD in the tailings. However, the mineral could not be found by optical microscopy or SEM-EDS. This suggests that the mineral has been weathered to a great extent, which poses a high risk of releasing elements of potential concern to the groundwater since danalite contains approximately 40% of the total Be and Zn concentrations in the tailings. Fluorine was mainly found in fluorite, Cu in chalcopyrite, and Bi in bismuthinite; which all showed signs of weathering in acidic condition in the uppermost part, subsequent with decreased concentrations, followed by accumulation peaks deeper down in the tailings correlated with Al. Tungsten was mainly found in scheelite; most grains were unweathered, but a few grains had altered rims or HFO on the mineral surfaces. Tin was mainly found in ferrohornblende, hedenbergite and grossular. Beryllium, Cu, F, and Zn has high potential to be released to the surrounding environment from the Smaltjärnen Repository, while W, Bi and Sn are relatively stable in the tailings. Most of the scheelite is intact and re-mining could, therefore, be a suitable remediation method that would both reduce the environmental impact and simultaneously support the supply of critical raw materials in the EU.

  • 7.
    Hällström, Lina
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Alakangas, Lena
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Martinsson, Olof
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Metal Release from Acidic and Near-Neutral pH-Conditions in Historical W, Cu and F Skarn Tailings at Yxsjöberg, Sweden2018In: 11th ICARD | IMWA | WISA MWD 2018 Conference: Risk to Opportunity / [ed] Wolkersdorfer, Ch.; Sartz, L.; Weber, A.; Burgess, J.; Tremblay, G., 2018, Vol. 1, p. 351-356Conference paper (Refereed)
    Abstract [en]

    Weathering products stored in the pore water and/or as easily soluble salts in historical skarn tailings containing Be, Bi, Cu, W, and Zn, were released in water soluble fraction in the upper-most acidic tailings, at the visual oxidation front (1.5m), and/or below 2.5m (pH>7). Thus, there is a risk that these metals can pollute receiving waters by neutral mine drainage. Re-mining the tailings could be a suitable remediation method that would both reduce the environmental impact and simultaneously support the supply of metals.

  • 8.
    Salifu, Musah
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Aiglsperger, Thomas
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Hällström, Lina
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Martinsson, Olof
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Billström, Kjell
    Department of Geological Sciences, Swedish Museum of Natural History, Frescativagen 40, Box 50007, 104 05, Stockholm, Sweden.
    Ingri, Johan
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Dold, Bernhard
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Alakangas, Lena
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Strontium (87Sr/86Sr) isotopes: A tracer for geochemical processes in mineralogically-complex mine wastes2018In: Applied Geochemistry, ISSN 0883-2927, E-ISSN 1872-9134, Vol. 99, p. 42-54Article in journal (Refereed)
    Abstract [en]

    Interpretation of geochemical data based primarily on elemental concentrations often lead to ambiguous results due to multiple potential sources including mineral weathering, atmospheric input, biological cycling, mineral precipitation and exchange processes. The 87Sr/86Sr ratio is however not fractionated by these processes. In this study, Sr isotope (87Sr/86Sr) ratios have been coupled with chemical data of Sr and Rb-bearing minerals, tailings and leachates (water-soluble) to gain insight into the geochemical processes occurring within the Yxsjöberg Cu-W mine tailings, Sweden. The tailings have been exposed to oxidizing conditions resulting in three geochemical zones namely (i) oxidized, (ii) transition and (iii) unoxidized zones. Leachates from the oxidized zone are acidic (pH = 3.6–4.5) and contain elevated concentrations of metals (e.g. Fe, Cu and Zn) and SO4. The low pH has also led to subsequent weathering of most silicates, releasing Al, Ca, Mg and Na into solution. The 87Sr/86Sr ratio in the tailings ranges from 0.84787 to 1.26640 in the oxidized zone, 0.92660–1.06788 in the transition zone, whilst the unoxidized zone has values between 0.76452 and 1.05169. For the leachates, the 87Sr/86Sr ratio ranges from 2.44479 to 5.87552 in the oxidized zone, 1.37404–1.68844 in the transition zone and 1.03697–2.16340 in the unoxidized zone. Mixing (between mineral weathering and atmospheric sources) was identified as the major process regulating the Sr composition of the tailings and leachates. The highly radiogenic signatures of the leachates in the oxidized zone suggests weathering of biotite, K-feldspar and muscovite. Despite the very radiogenic signatures in the oxidized zone, increments in Ca/K ratios, Be, Ce, Tl, Al, Fe and SO4 concentrations in the water-soluble phase were recorded in its lower parts which suggests the dissolution of amphibole, pyroxene, plagioclase, fluorite, gypsum, Al and Fe –(oxy) hydroxides as well as cation exchange by clay minerals. Presence of clay minerals has led to the partial retainment of radiogenic 87Sr/86Sr resulting in increased 87Sr/86Sr in the solid tailings material at these depths. The 87Sr/86Sr ratios of the water-soluble phase in the transition zone is similar to that of helvine and could indicate its dissolution. In the upper part of the oxidized zone, the 87Sr/86Sr ratios and trends of Be, Ca, SO4, Tl and Zn in the water-soluble phase suggest the dissolution of gypsum which precipitated from a leachate with the isotopic signature of helvine. In the lower part of the unoxidized zone, elevated concentrations of W were recorded suggesting scheelite weathering. But the 87Sr/86Sr ratios are higher than that expected from dissolution of scheelite and indicates additional processes. Possible sources include biotite weathering and groundwater. This study reveals that when interpreting geochemical processes in mine waste environments, 87Sr/86Sr should be considered in addition to chemical constituents, as this isotopic tracer offers better insights into discriminating between different solute sources.

  • 9.
    Hamberg, Roger
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Maurice, Christian
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Alakangas, Lena
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    The formation of unsaturated zones within cemented paste backfill mixtures: Effects on the release of copper, nickel, and zinc2018In: Environmental science and pollution research international, ISSN 0944-1344, E-ISSN 1614-7499, Vol. 25, no 21, p. 20809-20822Article in journal (Refereed)
    Abstract [en]

    Flooding of cemented paste backfill (CPB) filled mine workings is, commonly, a slow process and could lead to the formation of unsaturated zones within the CPB-fillings. This facilitates the oxidation of sulfide minerals, and thereby increases the risk of trace-metal leaching. Pyrrhotitic tailings from a gold mine (CT), containing elevated concentrations of Ni, Cu and Zn, were mixed with cement and/or fly ash (1-3 wt. %) to form CT-CPB-mixtures. Pyrrhotite oxidation progressed more extensively during unsaturated conditions, where acidity resulted in dissolution of the Ni, Cu, and Zn associated with amorphous Fe-precipitates and/or cementitious phases. The establishment of acidic, unsaturated conditions in CT-CBP:s with low fractions (1 wt. %) of binders increased the Cu-release (to be higher than that from CT), owing to the dissolution of Cu-associated amorphous Fe-precipitates. In CT-CPB:s with relatively high proportions of binder, acidity from pyrrhotite oxidation was buffered to a greater extent. At this stage, Zn-leaching increased due the occurrence of fly ash-specific Zn-species soluble in alkaline conditions. Irrespective of binder proportion and water saturation level, the Ni- and Zn-release were lower, compared to that in CT. Fractions of Ni, Zn, and Cu associated with acid-soluble phases or amorphous Fe-precipitates, susceptible to remobilization under acidic conditions, increased in tandem with binder fractions. Pyrrhotite oxidation occurred irrespective of the water saturation level in the CPB-mixtures. That in turn, poses an environmental risk, whereas a substantial proportion of Ni, Cu and Zn were associated with acid-soluble phases.

  • 10.
    Hamberg, Roger
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Maurice, Christian
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Alakangas, Lena
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Lowering the water saturation level in cemented paste backfill mixtures: Effect on the release of arsenic2017In: Minerals Engineering, ISSN 0892-6875, E-ISSN 1872-9444, Vol. 112, p. 84-91Article in journal (Refereed)
    Abstract [en]

    The Cemented Paste Backfill (CPB) method allows the mixing of dewatered tailings slurries with cementitious binders to backfill excavated underground workings. After mine closure, CPB workings are permanently flooded by rising groundwater. This flooding is considered beneficial for reducing the risk of acid generation associated with CPB containing sulphide minerals. In general, CPB workings are slowly flooded and the process may lead to regions with a low degree of water saturation to form within the CPB. This in turn, may increase oxygen ingress in the CPB, thereby prolonging oxidation of the minerals. To investigate the environmental impact of this oxidation, tailings containing elevated concentrations of arsenic (As) and pyrrhotite were handled via CPB. In this study, CPB mixtures containing 1–3 wt.% of cementitious binders and tailings was studied. The water saturation level in the CPB-mixtures was lowered as curing time extended. In mimicked flooded conditions, the mobility of As in the CPB mixtures was correlated with As-bearing cementitious phases that are sensitive to a reduction in the pH. In CPB-mixtures with lower proportions of binders, cementitious As-phases dissolved while the water saturation level decreased to form more stable As-phases. Increasing binder fractions, most of the cementitious As-phases persisted in the CPB while water saturation levels were lowered and release of As increased. Regardless of curing conditions, managing these tailings via the CPB method yielded increased mobility of As compared with that in the unmodified tailings; this resulted possibly from the formation of less acid-tolerant As species.

  • 11.
    Filcenco-Olteanu, Antoneta
    et al.
    Research and Development National Institute for Metals and Radioactive Resource.
    Alakangas, Lena
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Fiuza, Antoio
    University of Porto, Engineering Faculty.
    Zlǎgnean, Marius
    Research and Development National Institute for Metals and Radioactive Resource.
    Tomuş, Nicolae
    Research and Development National Institute for Metals and Radioactive Resource.
    Physical chemical characterization of historical mining waste and ARD prediction tests2017In: E3S Web of Conferences, E-ISSN 2267-1242, Vol. 18, no 4, article id 01031Article in journal (Refereed)
    Abstract [en]

    There are thousands of historical mine tailings and metallurgical residues present on inactive metal mining sites which have been abandoned. However, the potential release of dissolved metals, acidity, or suspended particulates from mine-waste dumps can be a serious and long-lasting problem. A variety of environmental impacts may occur at this abandoned mine sites and leading the list is acid generation, which is one of the main problems from metal mining. The objective of the present study was to characterize and evaluate the Romanian historical tailing of Sasar-Red Valley, near Baia Mare. This involved physical and chemical characterization of the materials and its acid generating potential. Sasar tailing impoundment contains 8.5 million m3 of tailings and occupies an area of 32.5 hectares. Tailings samples were collected from different depths in three sampling points, and characterized by grain size, chemical elements concentration, elements distribution of elements in depth, paste pH, acid-base account and net acid generation tests. Acid base accounting (ABA) tests in conjunction with net acid generation (NAG) tests classified the samples into the category of 'potentially acid generating'. This paper presents a synthesis of works performed in the Improve Resource Efficiency and Minimize Environmental Footprint (REMinE) project.

  • 12.
    Nyström, Elsa
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Kaasalainen, Hanna
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Alakangas, Lena
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Prevention of Sulfide Oxidation in Waste Rock using By-products and Industrial Remnants: a Suitability Study2017In: Mine Water & Circular Economy: A Green Congress / [ed] Wolkersdorfer, C.; Sartz, L.; Sillanpää, M. & Häkkinen, A, 2017, Vol. 2, p. 1170-1178Conference paper (Refereed)
    Abstract [en]

    Prevention and mitigation of acid rock drainage from mining are decisive for limiting environmental impact. Five by-products and industrial remnants (lime kiln dust, blast furnace slag, granulated blast furnace slag, cement kiln dust and fly ash) were investigated for their suitability to prevent acidity and metal(loid)s during leaching from highly sulfidic (50wt%, sulfide) waste rock in small scale laboratory test cells. Variations in pH and electrical conductivity in leachate allowed differentiation between the different materials. Lime kiln dust (5wt%) and fly ash (1 and 2.5wt%) were observed to be the most suitable materials to prevent acidity and metal(loid)s leaching.

  • 13.
    Nason, Peter
    et al.
    Univ Waterloo, Dept Earth & Environm Sci.
    Jia, Yu
    Department of Environment and Raw Material, Greenland Institute of Natural Resources.
    Maurice, Christian
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Alakangas, Lena
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Öhlander, Björn
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Biodegradation of Biosolids Under Aerobic Conditions: Implications for Cover Materials for Sulfide Mine Tailings Remediation2016In: Mine Water and the Environment, ISSN 1025-9112, E-ISSN 1616-1068, Vol. 35, no 3, p. 273-282Article in journal (Refereed)
    Abstract [en]

    Sewage sludge residue (biosolids) was investigated for its potential as a long-term tailings cover. Biosolids may prevent oxygen diffusion into underlying sulfide tailings through microbial aerobic biodegradation of organic matter. Biosolids were investigated at laboratory-, pilot-, and field-scale using analysis of total organic matter (TOM) mass reduction and O2, CO2, CH4 concentrations to quantify the biodegradation rate. A 156-day, open microcosm experiment, in which the loss of biosolids mass over time at differing temperatures, mimicking ambient (20–22 °C), mesophilic (34 °C), and thermophilic (50 °C) conditions, indicated that TOM biodegradation was best in the mesophilic temperature range, with 14.8, 27.2, and 26.7 % mass depletion at ambient, mesophilic, and thermophilic conditions, respectively. The data was correlated to field-scale data that evaluated biodegradation rates via decreasing O2 and increasing CO2 concentrations. Field biodegradation rates were less than laboratory rates because lower mean annual temperatures (0.6–0.7 °C) diminished microbial activity. A calibrated model indicates that 20 % of a field application of biosolids will degrade within 2 years. However, the rate declines with time due to exhaustion of the most readily degradable organic fraction. If biodegradation cannot be maintained, the long-term effectiveness of biosolids as a covering material for mine tailings remains a concern.

  • 14.
    Zhang, Wei
    et al.
    College of Land and Environment, Shenyang Agricultural University.
    Alakangas, Lena
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Wei, Zhongyi
    College of Land and Environment, Shenyang Agricultural University.
    Long, Jinghua
    Research Institute of Land Reclamation and Ecological Restoration, China University of Mining and Technology (Beijing).
    Geochemical evaluation of heavy metal migration in Pb-Zn tailings covered by different topsoils2016In: Journal of Geochemical Exploration, ISSN 0375-6742, E-ISSN 1879-1689, Vol. 165, p. 134-142Article in journal (Refereed)
    Abstract [en]

    Heavy metal migration was evaluated in Pb-Zn tailings covered by different topsoil constructions. The four topsoil constructions each had different interlayers: one with direct topsoiling above the tailings (CT); the second had a limestone interlayer between the tailings and topsoil with two geotextile layers set above and below the interlayer (SLS); the third had a lime interlayer, also with two geotextile layers (SL); and the fourth had a clay interlayer with two geotextile layers (SC). The topsoils were evaluated in a 210-day laboratory column leaching experiments and in a 3-year field cover application at an abandoned Pb-Zn tailings pond (northeastern China). The contents of Pb, Zn and Cd in the soils, leachates, interlayers and leaves of Amorpha fruticosa L. were analysed by inductively coupled plasma optical emission spectroscopy (ICP-OES).Results showed that the pH values of the leachates from the columns increased with time, from 6.5 to the range of 7.5 to 8.03, and the maximum in pH in C1 (tailings), C2 (CT), C3 (SLS), C4 (SL) and C5 (SC) appeared after the 180th day, at 7.85, 7.89, 7.78, 8.03, and 7.89, respectively. The topsoil effectively reduced the concentrations of Pb, Zn and Cd in the leachate, and the addition of a limestone or lime interlayer enhanced the efficiency, especially for Zn and Cd. The Pb, Zn and Cd concentrations in the topsoil that directly cover the tailings were appreciably less than the initial concentrations, resulting from the eluviation. The presence of a limestone or lime interlayer reduced the mobility of Zn and Cd, and a clay interlayer was effective in preventing the migration of Pb and Zn but had less impact on Cd.During the 3-year field experiment, the pH values of the topsoil increased slightly with time, from 7.15 to the range of 7.67 to 8.20. At the end of the experiment, Pb, Zn and Cd concentrations in the topsoil at the SLS, SL and SC plots showed little change compared with the initial value in 2012. Acid-soluble Pb, Zn and Cd concentrations of the upper soil (0–0.1 m) at CT increased from 0.19, 1.95 and 0.11 mg kg− 1 in 2012 to 1.82, 32.87 and 0.56 mg kg− 1 in 2015, indicating that acid-soluble heavy metals migrated from tailings to topsoil. Acid-soluble Cd in topsoil and in the interlayer showed a small increase at plot SC, indicating that Cd may migrate through the clay layer to topsoil with pore water. The Pb contents in leaves at SLS and SL were 2.38 and 3.04 mg kg− 1, which were appreciably lower than at CT and SC, and the Zn and Cd contents in leaves at CT were 45.78 and 0.26 mg kg− 1, which were higher than at SLS, SL and SC. Topsoiling with an interlayer could be a reliable technique for preventing toxic elements from moving downward or upward during ecological restoration of tailings ponds.

  • 15.
    Siren, Susanne
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Maurice, Christian
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Alakangas, Lena
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Green liquor dregs in mine waste remediation, from laboratory investigations to field application2016In: Mining Meets Wate: conflict and solutions IMWA 2016 in Leipzig, Germany, July 11-15, 2016 / [ed] Carsten Drebenstedt; Michael Paul, Freiberg: TU Bergakademie Freiberg, Institute of Mining and Special Civil Engineering , 2016, p. 706-713Conference paper (Refereed)
    Abstract [en]

    The oxidation of sulphides in mine wastes is a possible threat to the environment as it has potential to generate acid rock drainage (ARD). A way to reduce ARD formation is to apply a soil cover to reduce oxygen fluxes and water infiltration to the underlying reactive wastes. A typical mine waste cover in Sweden consists of a compacted sealing layer of a fine grained till overlaid by an on-compacted protection layer. However, a fine grained till with low enough hydraulic conductivity (HC) can be difficult to find in the vicinity of the mine and it might be necessary to mix it with a fine grained material. In this study a mixture of till and a residue from pulp and paper production, Green Liquor Dregs (GLD) was studied in laboratory and in a pilot cell study. The objective of the laboratory study was to investigate if an addition of GLD will improve the HC of tills with different clay contents. The results show that HC of the different tills studied decreases with addition of 5-10 w.% of GLD, except from the clayey till that already had a low HC without addition of GLD. In the pilot scale study a cell was constructed to investigate the feasibility to compact a sealing layer of a fine grained till and 10 w. % of GLD. The pilot scale study shows that it can be difficult to reach a high compaction degree in the field. However, it does not necessarily mean that the HC of the sealing layer will increase. In fact the laboratory study shows the opposite trend, a decrease in HC with a decrease in dry density for tills with low clay content. The main conclusion of the study is that addition of GLD can be an alternative option to improve the properties of a local till that alone does not meet the requirements for HC.

  • 16.
    Alakangas, Lena
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Rasmussen, Torklid Maack
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Project: Development, Evaluation and Optimization of Measures to Reduce the Impact on the Environment from Mining Activities in Northern Regions2016Other (Other (popular science, discussion, etc.))
    Abstract [en]

    Min-North is a transnational project financed by the Interreg Nord program and coordinated by LTU. The project is a cooperation between Geological survey of Finland, GTK, Oulo University (Finland), The Arctic University of Norway, UiT and several (>17) small and large enterprises and mining companies in the northern region with expertise within geology, waste management, geophysics and geochemistry. The overall goal is to reduce the environmental impacts of mining in the northern regions by developing, evaluating, optimizing environmental techniques. In Sweden, geophysical and geochemical techniques will be integrated to develop a 4D model for tracing pollution transport in the mine waste, mine areas and in(to) the surroundings.

  • 17.
    Alakangas, Lena
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Sandström, Åke
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Minerals and Metallurgical Engineering.
    Rosenkranz, Jan
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Minerals and Metallurgical Engineering.
    Martinsson, Olof
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Hällström, Lina
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Project: Improve Resource Efficiency and Minimize Environmental Footprint2016Other (Other (popular science, discussion, etc.))
    Abstract [en]

    The REMinE project is organized in five work packages that comprise: detailedcharacterization and risk assessment of the mine wastes selected (WP2), identification of new processing methods for mine waste (WP3), characterization and risk assessment of the remaining residuals (WP4), outlining business opportunities and environmental impact in a conceptual model for sustainable mining (WP5). The project comprises case studies of historical mine wastes from three different European countries, namely Portugal, Romania and Sweden. The interdisciplinary research collaboration in this project is innovative in the sense that separation of minerals and extraction of metals not only are basedon technical and economic gain but also considers the environmental perspective.

  • 18.
    Hamberg, Roger
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Bark, Glenn
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Maurice, Christian
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Alakangas, Lena
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Release of arsenic from cyanidation tailings2016In: Minerals Engineering, ISSN 0892-6875, E-ISSN 1872-9444, Vol. 93, p. 57-64Article in journal (Refereed)
    Abstract [en]

    At a gold mine in northern Sweden, gold occurring as inclusions in pyrrhotite and arsenopyrite is leached by cyanidation of the ore. The main sulphide minerals in the ore are pyrrhotite and arsenopyrite. Effluents from the cyanidation process are treated with Fe2(SO4)3 to form Fe-precipitates suitable for the co-precipitation of As. The aim of this study was to perform static and kinetic leaching tests on the ore and tailings to define geochemical processes governing As mobility. Sequential leaching tests suggested that the majority of dissolved As deriving from the sulphide fraction in the ore was incorporated in newly formed Fe-precipitates in the tailings. The mobility of As in the tailings was therefore mainly dependent on the stability of these As-bearing Fe-precipitates. Weathering cell tests (WCT) involving 31 weekly cycles of wetting and air exposure were conducted to assess the stability of the As in the tailings under accelerated weathering conditions. The first stage of the WCT was characterized by a pH ≈ 5 and low As leaching, probably driven by the dissolution of amorphous Fe-As species. In the second stage of the WCT, leaching of Fe, S and As increased and the pH decreased to <3.5. An increase of the leachate’s molar Fe/S-ratio suggested that pyrrhotite oxidation was occurring. The falling pH destabilized As-bearing Fe-precipitates, causing further As release. The total As release during the WCT corresponded to only a small proportion of the tailings’ total As content. The accelerated As-leaching observed towards the end of the WCT could thus indicate that its release could increase progressively over time.

  • 19.
    Hamberg, Roger
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Alakangas, Lena
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Maurice, Christian
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    The release of arsenic from cyanidation tailings2016In: Arsenic Research and Global Sustainability: Proceedings of the 6th International Congress on Arsenic in the Environment, AS 2016 / [ed] Bhattacharya, Prosun; Vahter, Marie; Jarsjo, Jerker; Kumpiene, Jurate; Charlotte, Sparrenbom, London: CRC Press, 2016, p. 201-202Conference paper (Refereed)
    Abstract [en]

    Tailings from a gold mine containing 1000 mg/kg of As were used to predict the release of As over an extended period of time. Post-cyanide mine processes were aiming to form arsenates and Fe-hydrates for effective As-immobilization. Speciation of the As in ore and tailings samples revealed that mining processes have dissolved the majority of the arsenopyrite in the ore, causing secondary As phases to co-precipitate with newly formed Fe-hydrates. Weathering Cell Tests (WCT) were conducted to assess the effect of weathering on the stability of As in the tailings. As-bearing Fe-hydrates remained intact during the early stages of the WCT. During later stages of the WCT, the release of As, Fe and S increased due to pyrrhotite oxidation and the destabilization of As-bearing Fe-hydrates. Low proportions of As was released in WCT, but additional pyrrhotite oxidation as pH falling to < 3 could further destabilize As-bearing Fe-hydrates

  • 20.
    Zhang, Wei
    et al.
    College of Land and Environment, Shenyang Agricultural University, Shenyang.
    Long, Jinghua
    Research Institute of Land Reclamation and Ecological Restoration, China University of Mining and Technology (Beijing).
    Wei, Zhongyi
    College of Land and Environment, Shenyang Agricultural University, Shenyang.
    Alakangas, Lena
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Vertical distribution and historical loss estimation of heavy metals in an abandoned tailings pond at HTM copper mine, northeastern China2016In: Environmental Earth Sciences, ISSN 1866-6280, E-ISSN 1866-6299, Vol. 75, no 22, article id 1462Article in journal (Refereed)
    Abstract [en]

    In the tailings pond of the Hongtou Mountain (HTM) copper mine in northeastern China, four sampling points were set at intervals of 80 m along the discharge direction of the tailings slurry to investigate the vertical distribution characteristics of heavy metals in shallow layer (0–5 m) tailings. In addition, 18 sampling points were set by a grid method (50 m × 50 m) to estimate the historical loss amount of contaminants from the surface layer (0–1.2 m) of the HTM tailings pond. Tailings samples were taken at every 0.2 m, and the pH value, the total content and acid-soluble fraction of heavy metals and chemical compositions were determined following the standard methods. The results showed that the pH values of tailings ranged from 3.01 to 8.11, which increased with depths from 0 to 2.2 m, and varied between pH values of 7.0 and 7.5 in 2.2–5 m. Cu, Zn, Cd and S were the major contaminants in the tailings. The total Cu content was higher at the downstream sampling points near the dam. Zn and Cd were higher at the upstream sampling points near the discharge. Three distinct zones (oxidised zone, cemented layer and unoxidised zone) were found in the HTM tailings pond. The depth of the oxidised zone was 0.4 m, and the elements in the oxidised tailings were obviously lower due to the sulphides oxidation and acid mine drainage. Cu was enriched in the cemented layer, and the Cu content reached values between 1200 and 3000 mg/kg, which were 1.5–3 times higher than the average value. Zn, Cd, Ni and Fe were also slightly elevated in the cemented layer. Below the groundwater table, the acid-soluble fraction of Cu, Zn and Cd was relatively stable at a lower level and showed insignificant variations, as the cemented layer and groundwater could efficiently prevent the oxidation process. The amount of Cu, Zn and Cd leaving the tailings pond with drainage water was 8.08, 21.60 and 72.93%, respectively, of the amount released from oxidation. Most of the Cu released from oxidation was retained in the cemented layer. The total mass of S, Zn and Cd released from the tailings to surrounding ecosystems was estimated approximately 762.75 t, 6997.5 and 86.06 kg, respectively, in the last 20 years.

  • 21.
    Siren, Susanne
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Maurice, Christian
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Alakangas, Lena
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Evaluation of mixtures of green liquor dregs and till for application as a sealing layer on sulfidic mine waste2015Conference paper (Refereed)
  • 22. Jia, Yu
    et al.
    Nason, Peter
    Maurice, Christian
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Alakangas, Lena
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Öhlander, Björn
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Investigation of biosolids degradation under flooded environments for use in underwater cover designs for mine tailing remediation2015In: Environmental science and pollution research international, ISSN 0944-1344, E-ISSN 1614-7499, Vol. 22, no 13, p. 10047-10057Article in journal (Refereed)
    Abstract [en]

    To evaluate the potential suitability of digested sewage sludge (frequently termed biosolids) for use as underwater cover material for mine waste tailings, the degradability of biosolids at 20 − 22 °C under flooded anaerobic conditions was evaluated during incubation for 230 days. Leaching of elements from the flooded anaerobic system was also evaluated. Biosolid degradation was confirmed by the generation and accumulation of CH4 and CO2. Specifically, approximately 1.65 mmoL gas/g biosolids was generated as a result of incubation, corresponding to degradation of 7.68 % of the organic matter, and the residue was stable at the end of the laboratory experiment. Under field conditions in northern Sweden, it is expected that the degradation rate will be much slower than that observed in the present study (Nason et al. Environ Earth Sci 70:30933105, 2013). Although the majority of biosolid fractions (>92 %) were shown to be recalcitrant during the incubation period, long-term monitoring of further degradability of residue is necessary. The leaching results showed that most of the metals and metalloids leached from the biosolids at day 230 were below the limit value for non-hazardous waste, although Ni was the only element approximately three times higher than the limit value for inert material at the landfill site. In conclusion, biosolids have potential for use as covering material for underwater storage of tailings based on their biodegradability and leaching of elements.

  • 23. Rodríguez, Nathalie Pérez
    et al.
    Khoshkhoo, Mohammad
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Minerals and Metallurgical Engineering.
    Sandström, Åke
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Minerals and Metallurgical Engineering.
    Rodushkin, Ilya
    Alakangas, Lena
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Öhlander, Björn
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Isotopic signature of Cu and Fe during bioleaching and electrochemical leaching of a chalcopyrite concentrate2015In: International Journal of Mineral Processing, ISSN 0301-7516, E-ISSN 1879-3525, Vol. 134, p. 58-65Article in journal (Refereed)
    Abstract [en]

    Bioleaching is an important process in metallurgy and in environmental sciences, either for the acquisition of metals or for the formation of acid rock drainage. In this study the implications of the processes during bioleaching of a pyritic chalcopyrite concentrate were analysed regarding its Cu and Fe isotope fractionation. The development of the redox potential during the bioleaching experiment was then simulated in an electrochemical cell in absence of microorganisms to investigate the effect of microbial activity on the Cu and Fe isotope fractionations. The leaching experiments were performed for 28 days at 45 °C with a solid content of 2.5% (w/v) at pH 1.5. It was found that Cu dissolution efficiency was similar in both experiments and the leaching curves were linear with no sign of passivation due to presence of pyrite. The heavy Cu isotope (δ65Cu) was leached more easily and as a result the leachate was enriched with the heavy Cu isotope at the beginning of both experiments and as the leaching progressed δ65Cu values in the leachate became similar to the ones of the chalcopyrite concentrate, confirming an equilibrium fractionation happening in a closed system. There was no distinct difference in the Cu and Fe isotope fractionations in absence and presence of microorganisms. Finally based on Cu and Fe isotope signatures, a simplified method is suggested for the estimation of the leaching extent during the oxidisation of sulphide materials in natural systems.

  • 24.
    Hamberg, Roger
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Maurice, Christian
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Alakangas, Lena
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    The use of low binder proportions in cemented paste backfill: Effects on As-leaching2015In: Minerals Engineering, ISSN 0892-6875, E-ISSN 1872-9444, Vol. 78, p. 74-82Article in journal (Refereed)
    Abstract [en]

    Gold is extracted by cyanide leaching from inclusions in arsenopyrite at a mine in the north of Sweden. The major ore mineral assemblage consists of pyrrhotite and arsenopyrite–loellingite. Arsenopyrite is assumed to be oxidized during cyanidation and the stability of secondary As-phases needs to be assessed. One way of managing such tailings is to convert them into a monolithic mass by using a method called cemented paste backfill (CPB). In CPB, tailings are traditionally mixed with water (typically 25% by weight) and small amounts (3–7%) of binders, and backfilled into excavated underground areas. To investigate the release of arsenic (As) from CPB prepared from As-rich tailings, tailings containing approx. 1000 ppm of As, mainly in the form of As-bearing iron (Fe)-precipitates (FEP), were mixed with small quantities (1–3%) of biofuel fly ash (BFA), ordinary cement, and water to produce monolithic CPB masses. CPB-recipes were designed to meet the strength demand of 200 kPa, stated by the mine operators. Tank leaching tests (TLT) and the weathering cell test (WCT) were used to compare the leaching behavior of As in unmodified tailings and CPB-materials. Results from the leaching tests (TLT and WCT) showed that the inclusion of As-rich tailings into a cementitious matrix increased leaching of As. This behavior could partially be explained by an increase of pH where As sorbed to FEPs becomes unstable. In the CPB mixtures, small (>1%) proportions of the total As in the solid material was released from less acid-tolerant species (i.e. Ca-arsenates and As bonded to cementitious phases). Unmodified tailings generated an acidic environment in flooded conditions at which As-bearing FEPs were stable. Acid was added to the crushed CPB materials during later stages of the WCTs to mimic the effects of weathering. This increased the leaching of Fe and had minor effects on that of As but did not affect S-leaching.

  • 25.
    Nason, Peter
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Johnson, Raymond H.
    Crustal Geophysics and Geochemistry Science Center, U.S. Geological Survey, Denver Federal Center.
    Neuschütz, Clara
    Niras, Box 70375, SE-107 24, Stockholm.
    Alakangas, Lena
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Öhlander, Björn
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Alternative Waste Residue Materials for passive in-situ prevention of sulfide-mine tailings oxidation: A Field Evaluation2014In: Journal of Hazardous Materials, ISSN 0304-3894, E-ISSN 1873-3336, Vol. 267, p. 245-254Article in journal (Refereed)
    Abstract [en]

    Novel solutions for sulfide-mine tailings remediation were evaluated in field-scale experiments on a former tailings repository in northern Sweden. Uncovered sulfide-tailings were compared to sewage-sludge biosolid amended tailings over 2 years. An application of a 0.2 m single-layer sewage-sludge amendment was unsuccessful at preventing oxygen ingress to underlying tailings. It merely slowed the sulfide-oxidation rate by 20%. In addition, sludge-derived metals (Cu, Ni, Fe, and Zn) migrated and precipitated at the tailings-to-sludge interface. By using an additional 0.6 m thick fly-ash sealing layer underlying the sewage sludge layer, a solution to mitigate oxygen transport to the underlying tailings and minimize sulfide-oxidation was found. The fly-ash acted as a hardened physical barrier that prevented oxygen diffusion and provided a trap for sludge-borne metals. Nevertheless, the biosolid application hampered the application, despite the advances in the effectiveness of the fly-ash layer, as sludge-borne nitrate leached through the cover system into the underlying tailings, oxidizing pyrite. This created a 0.3 m deep oxidized zone in 6-years. This study highlights that using sewage sludge in unconventional cover systems is not always a practical solution for the remediation of sulfide-bearing mine tailings to mitigate against sulfide weathering and acid rock drainage formation

  • 26.
    Jia, Yu
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Nason, Peter
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Alakangas, Lena
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Maurice, Christian
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Öhlander, Björn
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Degradation of digested sewage sludge residue under anaerobic conditions for mine tailings remediation2014In: Environmental Earth Sciences, ISSN 1866-6280, E-ISSN 1866-6299, Vol. 72, no 9, p. 3643-3654Article in journal (Refereed)
    Abstract [en]

    Previous studies showed that 85 % of total organic matter (TOM) in digested sewage sludge (biosolids) used as a sealing layer material over sulfide tailings at the Kristineberg Mine, northern Sweden had been degraded 8 years after application, resulting in a TOM reduction from 78 % to 14 %. To achieve a better understanding of the field observations, laboratory studies were performed to evaluate biodegradation rates of the TOM under anaerobic conditions. Results reveal that the original biosolid consisted of ca. 60 % TOM (48.0 % lignin and 11.8 % carbohydrates) that had not been fully degraded. The incubation experiments proved that 27.8 % TOM in the biosolid was further degraded anaerobically at 20-22 C during the 230 d incubation period, and that a plateau to the biodegradation rate was approached. Based on model results, the degradation constant was found to be 0.0125 (day-1). The calculated theoretical gas formation potential was ca. 50 % higher than the modeled results based on the average degradation rate. Cumulated H2S equated to 0.65 µmoL*g-1 of biosolid at 230 d. However, the large sulfurous compounds reservoir (1.76 g SO42- kg-1 biosolid) together with anaerobic conditions, can generate high concentrations of this gas over a long-term perspective. Due to the rate of biodegradability identified via anaerobic processes, the function of the biosolid to serve as an effective barrier to inhibit oxygen migration to underlying tailings, may decrease over time. However, a lack of readily degradable organic fractions in the biosolid and a large fraction of organic matter that was recalcitrant to degradation suggests a longer degradation duration, which would prolong the biosolid material’s function and integrity.

  • 27.
    Villain, Lucile
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Sundström, Nils
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Perttu, Nils
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Alakangas, Lena
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Öhlander, Björn
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Evaluation of the effectiveness of backfilling and sealing at an open-pit mine using ground penetrating radar and geoelectrical surveys, Kimheden, northern Sweden2014In: Environmental Earth Sciences, ISSN 1866-6280, E-ISSN 1866-6299, Vol. 73, no 8, p. 4495-4509Article in journal (Refereed)
    Abstract [en]

    At Kimheden, a small copper mine in northern Sweden, reclamation of the two open pits was investigated using ground penetrating radar and geoelectrical multiple-gradient array measurements. The pits had been backfilled with waste rock, with a dry cover being applied on top in 1996 in order to reduce the influx of oxygen to the sulphidic mine waste and the subsequent production of acid mine drainage. The dry cover consists of a sealing layer of clayey till and a protective layer of unsorted till. As geochemical sampling in the drainage from the pits had previously revealed the continued release of contaminating oxidation products, the purpose of the geophysical survey undertaken in 2010 was to identify deficiencies in the cover or other pathways for oxygen to reach the waste rock. The radar images did not reveal any damage in the sealing layer but risks of deterioration of the cover in the long term were identified with both the radar and geoelectrical data. The radar localised regions of thinner protective layer where the sealing layer could be exposed to frost action. The geoelectrical measurements indicated the existence of seepage through the dry cover that presented a risk of erosion of the sealing layer. 2-D inversion of geoelectrical data also imaged some pathways of groundwater around the main pit. The results from the geophysical investigations were used together with other site data in order to show that both deficiencies in the cover and superficial fractures in the pit walls may explain an ongoing influx of oxygen to the mine waste.

  • 28.
    Nason, Peter
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Alakangas, Lena
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Öhlander, Björn
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Impact of Sewage Sludge on Groundwater Quality at a Formerly Remediated Tailings Impoundment2014In: Mine Water and the Environment, ISSN 1025-9112, E-ISSN 1616-1068, Vol. 33, no 1, p. 66-78Article in journal (Refereed)
    Abstract [en]

    Sewage sludge can be a suitable, organic-rich substrate to promote vegetation ofsulfide-mine tailings, but it may contain contaminants, that, when oxidized, canadversely affect underlying groundwater systems. The geochemical impact of asurface application of 12,000 metric tons of anaerobically-digested sewage sludge on the groundwater quality of a remediated sulfide-tailings impoundment in northern Sweden was evaluated to determine if sludge-borne metals and nitrate were released to the underlying groundwater system. Two years of data from a field-scale groundwater monitoring programme initiated just before the sludge application was compared to groundwater data from 1998-2006. Grass was successfully established within two years. However, until that occurred, elevated concentrations of sludge-borne metals (Cu, Ni, Pb, Zn) were released to the underlying groundwater. In addition, the release of nitrate likely exacerbated metal concentrations by providing an oxidant for pyrite in the underlying tailings. The release was periodic due to the establishment of the grass, which immobilized metals and nitrate in the sludge. Metals bound asorgano-metallic complexes, due to dissolved organic carbon released from the sludge, migrated across the tailings impoundment. Model simulations indicate that the plume will take six years to exit the groundwater environment. Though the impacts are relatively short-term, this type of application should be reconsidered in the future.

  • 29.
    Alakangas, Lena
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Maurice, Christian
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Macsik, Josef
    Strategic services & Sustainable Development at Ecoloop.
    Nyström, Elsa
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Sandström, Nadia
    Luleå tekniska universitet.
    Andersson-Wikström, Alexandra
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Hällström, Lina
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Kartläggning av restprodukter för efterbehandling och inhibering av gruvavfall: funktion tillgång och logistik2014Report (Other academic)
  • 30.
    Lu, Jinmei
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Alakangas, Lena
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Wanhainen, Christina
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Metal mobilization under alkaline conditions in ash-covered tailings2014In: Journal of Environmental Management, ISSN 0301-4797, E-ISSN 1095-8630, Vol. 139, p. 38-49Article in journal (Refereed)
    Abstract [en]

    The aim of this study was to determine element mobilization and accumulation in mill tailings under alkaline conditions. The tailings were covered with 50 cm of fly ash, and above a sludge layer. The tailings were geochemically and mineralogically investigated. Sulfides, such as pyrrhotite, sphalerite and galena along with gangue minerals such as dolomite, calcite, micas, chlorite, epidote, Mn-pyroxene and rhodonite were identified in the unoxidized tailings. The dissolution of the fly ash layer resulted in a high pH (close to 12) in the underlying tailings. This, together with the presence of organic matter, increased the weathering of the tailings and mobilization of elements in the uppermost 47 cm of the tailings. All primary minerals were depleted, except quartz and feldspar which were covered by blurry secondary carbonates. Sulfide-associated elements such as Cd, Fe, Pb, S and Zn and silicate-associated elements such as Fe, Mg and Mn were released from the depletion zone and accumulated deeper down in the tailings where the pH decreased to circum-neutral. Sequential extraction suggests that Cd, Cu, Fe, Pb, S and Zn were retained deeper down in the tailings and were mainly associated with the sulfide phase. Calcium, Cr, K and Ni released from the ash layer were accumulated in the uppermost depletion zone of the tailings

  • 31.
    Alakangas, Lena
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Bark, Glenn
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Ericsson, Magnus
    Luleå University of Technology, Department of Business Administration, Technology and Social Sciences, Social Sciences.
    Martinsson, Olof
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Söderholm, Patrik
    Luleå University of Technology, Department of Business Administration, Technology and Social Sciences, Social Sciences.
    Wanhainen, Christina
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Weihed, Pär
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Widerlund, Anders
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Öhlander, Björn
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Norrbottens malm- och mineralresurs och dess potentiella betydelse för innovation, samhälle och miljö2014Report (Other academic)
    Abstract [sv]

    Gruvindustrins betydelse för samhällsutveckling och infrastruktur i Sverige och inte minst i Norrbottens län är mycket stor. De geologiska förutsättningarna att hitta nya brytvärda förekomster i Norrbotten är goda. Länet är tillsammans med Västerbotten en av Europas viktigaste regioner för utvinning av metaller. Det syns också i den nyligen framtagna regionala mineralstrategin för Norrbotten och Västerbotten. Visionen för den regionala mineralstrategin: ”Genom långsiktigt hållbart nyttjande av Norrbottens och Västerbottens läns mineralresurser har ytterligare tillväxt skapats i regionen och hela Sverige. Vi har utvecklat och stärkt vår ställning som ledande gruv- och mineralnation.”Eftersom framtidspotentialen för gruvnäringen är mycket god men okunnigheten hos både allmänhet och beslutsfattare om näringens betydelse för innovation och samhällsutveckling är stor, kopplat med en utbredd oro för miljöpåverkan, måste dessa viktiga framtidsfrågor belysas. Med finansiering från Länsstyrelsen i Norrbotten bedrevs därför under första hälften av 2014 en förstudie som syftade till att sammanfatta kunskapsläget om framtidens gruvindustri i Norrbotten. Resultaten av förstudien redovisas i den här rapporten. En viktig slutsats är att det under nästa strukturfondsperiod (med start 2015) behövs ett framtidsinriktat forskningsprogram för att belysa de möjligheter som finns. Denna förstudie utgör grund för en kommande ansökan till strukturfonderna. Kompetensen som finns vid Luleå tekniska universitet, Sveriges centrum för gruvrelaterad forskning och utbildning, bör användas för att studera troliga framtidsmöjligheter och hur de ska kunna användas för att få en så positiv utveckling som möjligt för länet. Projektet bör innehålla följande tre huvudinriktningar, som naturligtvis hör ihop:Vilka malm- och mineralresurser finns det potential för i Norrbotten, och vilka kommer sannolikt att exploateras i framtiden?Vad kommer den exploateringen att ha för betydelse för innovation och samhällsutveckling?Vad kommer den exploateringen att få för miljöeffekter och hur ska man göra för att minska miljöbelastningen?En annan slutsats är att nedlagda gruvområden inte måste ses som förstörd natur. Betydande mervärden som gruvturism skulle kunna skapas om vilja, kreativitet och beslutsamhet finns. Detta är ett givet utvecklingsområde där småföretag och entreprenörer kan göra stor insats om de politiska och myndighetsmässiga förutsättningarna finns. Dessa aspekter skulle också kunna belysas i det föreslagna forskningsprogrammet eller i ett eget projekt.

  • 32.
    Alakangas, Lena
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Hamberg, Roger
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Project: ERA-MIN project "Tools for sustainable gold mining in EU"2014Other (Other (popular science, discussion, etc.))
    Abstract [en]

    This research identifies and evaluates environmental impacts and economical challenges of gold mining in Finland, Sweden, Portugal, Romania, Poland and Ireland. The focus of this project is in gold exploration, mineral processing, water treatment, waste management, environmental monitoring, risk assessment and socio-economic impacts of gold mining. Finasieras av Vinnova

  • 33.
    Alakangas, Lena
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Project: Kolarctic ENBI EnviMIne2014Other (Other (popular science, discussion, etc.))
    Abstract [en]

    The objectives of the project are to develop a methodology for environmentally safe mine closure under specific conditions in the Barents region by cross border cooperation, exchange experiences and scientific knowledge.

  • 34.
    Alakangas, Lena
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Maurice, Christian
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Nyström, Elsa
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Siren, Susanne
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Project: Utilization of Industrial Residuals for Prevention of Sulphide Oxidation in Mine Wastes2014Other (Other (popular science, discussion, etc.))
  • 35.
    Alakangas, Lena
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Maurice, Christian
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Projekt: Användning av restprodukter för förhindrande sulfid oxidation i reaktivt gruvavfall- en förstudie2014Other (Other (popular science, discussion, etc.))
    Abstract [sv]

    En inventering av lämpliga restmaterial för efterbehandling och behandling av gruvavfall har genomförts och resulterat i en rapport

  • 36.
    Rodríguez, Nathalie Pérez
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Langella, Francesca
    Institute for Microbiology, Friedrich-Schiller-University, Jena.
    Rodushkin, Ilya
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Engström, Emma
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Kothe, Erika
    Institute for Microbiology, Friedrich-Schiller-University, Jena.
    Alakangas, Lena
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Öhlander, Björn
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    The role of bacterial consortium and organic amendment in Cu and Fe isotope fractionation in plants on a polluted mine site2014In: Environmental science and pollution research international, ISSN 0944-1344, E-ISSN 1614-7499, Vol. 21, no 11, p. 6836-6844Article in journal (Refereed)
    Abstract [en]

    Copper and iron isotope fractionation by plant uptake and translocation is a matter of current research. As a way to apply the use of Cu and Fe stable isotopes in the phytoremediation of contaminated sites, the effects of organic amendment and microbial addition in a mine spoiled soil seeded with Helianthus annuus in pot experiments and field trials were studied. Results show that the addition of a microbial consortium of ten bacterial strains has an influence on Cu and Fe isotope fractionation by the uptake and translocation in pot experiments, with an increase in average of 0.99‰ for the δ65Cu values from soil to roots. In the field trial, the amendment with the addition of bacteria and mycorrhiza as single and double inoculation enriches the leaves in 65Cu compared to the soil. As a result of the same trial, the δ56Fe values in the leaves are lower than those from the bulk soil, although some differences are seen according to the amendment used. Siderophores, possibly released by the bacterial consortium, can be responsible for this change in the Cu and Fe fractionation. The overall isotopic fractionation trend for Cu and Fe does not vary for pots and field experiments with or without bacteria. However variations in specific metabolic pathways related to metal-organic complexation and weathering can modify particular isotopic signatures.

  • 37.
    Rodríguez, Nathalie Pérez
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Engström, Emma
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Rodushkin, Ilya
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Nason, Peter
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Alakangas, Lena
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Öhlander, Björn
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Copper and iron isotope fractionation in mine tailings at the Laver and Kristineberg mines, northern Sweden2013In: Applied Geochemistry, ISSN 0883-2927, E-ISSN 1872-9134, Vol. 32, p. 204-215Article in journal (Refereed)
    Abstract [en]

    Previous research has shown that Cu and Fe isotopes are fractionated by dissolution and precipitation reactions driven by changing redox conditions. In this study, Cu isotope composition (65Cu/63Cu ratios) was studied in profiles through sulfide-bearing tailings at the former Cu mine at Laver and in a pilot-scale test cell at the Kristineberg mine, both in northern Sweden. The profile at Kristineberg was also analysed for Fe isotope composition (56Fe/54Fe ratios). At both sites sulfide oxidation resulted in an enrichment of the lighter Cu isotope in the oxidised zone of the tailings compared to the original isotope ratio, probably due to preferential losses of the heavier Cu isotope into the liquid phase during oxidation of sulfides. In a zone with secondary enrichment of Cu, located just below the oxidation front at Laver, δ65Cu (compared to ERM-AE633) was as low as -4.35 ± 0.02‰, which can be compared to the original value of 1.31 ± 0.03‰ in the unoxidised tailings. Precipitation of covellite in the secondary Cu enrichment zone explains this fractionation. The Fe isotopic composition in the Kristineberg profile is similar in the oxidised zone and in the unoxidised zone, with average δ56Fe values (relative to the IRMM-014) of -0.58± 0.06‰ and -0.49 ± 0.05‰, respectively. At the well-defined oxidation front, δ56Fe was less negative, -0.24 ± 0.01 ‰. Processes such as Fe(II)-Fe(III) equilibrium and precipitation of Fe-(oxy)hydroxides at the oxidation front are assumed to cause this Fe isotope fractionation. This field study provides additional support for the importance of redox processes for the isotopic composition of Cu and Fe in natural systems.

  • 38.
    Lu, Jinmei
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Alakangas, Lena
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Jia, Yu
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Gotthardsson, Jenny
    Boliden Mineral AB.
    Evaluation of the application of dry covers over carbonate-rich sulphide tailings2013In: Journal of Hazardous Materials, ISSN 0304-3894, E-ISSN 1873-3336, Vol. 244-245, p. 180-194Article in journal (Refereed)
    Abstract [en]

    In this study, four ten years test areas with covered tailings were geochemically evaluated. Three areas were covered with a fly ash and an overlying sludge layer, and one only with a sludge cover, originating from paper mills. The accumulation of As, Fe and Pb in sludge layers, originating from air-borne dust and the depletion of K, Na and P from both cover layers were observed. High release of elements from tailings was observed in the comparison profile due to oxidation and weathering of tailings. In only sludge covered area, the leaching of elements from tailings decreased. In the profiles with thin ash (20 cm and 30 cm), most elements were retained in tailings with pH 7-9. In the profile with the thickest ash (50 cm), elements such as As, Cd, Cu, Mg, Mn, Pb, S and Zn were depleted in the uppermost tailings with pH above 11 and retained deeper in the zone with pH 7-8, which implied that large quantities of fly ash increased the oxidation and weathering of tailings and mobility of elements. Elements excluding K, never reached the groundwater in high concentrations in the covered areas, while the comparison area had high Ca, K, Mn and S concentrations

  • 39.
    Rodríguez, Nathalie Pérez
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Adlassnig, Wolfram
    Core Facility Cell Imaging and Ultrastructure Research, Univeristy of Vienna.
    Rodushkin, Ilya
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Alakangas, Lena
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Öhlander, Björn
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Isotopic fractionation of Cu in biofilms from a historic mining site2013In: Mineralogical magazine, ISSN 0026-461X, E-ISSN 1471-8022, Vol. 77, no 5, p. 1950-Article in journal (Refereed)
  • 40.
    Alakangas, Lena
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Dagli, Deniz
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Knutsson, Sven
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Literature review on potential geochemical and geotechnical effects of adopting paste technology under cold climate conditions2013Report (Other academic)
    Abstract [en]

    The purpose of this literature review is to summarize the recent research regarding geochemical and geotechnical stability of paste tailings, identify knowledge gaps and future research needs. The present study has been conducted by the Division of Geosciences and Environmental Engineering together with the Division of Mining and Geotechnical Engineering at Luleå University of Technology on behalf of Boliden Mineral, LKAB and Outotec.A survey conducted by MEND (Mine Environment Neutral Drainage) in 2006 on the environmental effects related to the use of paste tailings summarizes that only a few studies had been performed about long-term effects on the surface and groundwater quality. Instead, the focus had been on the additives and the strength of the paste. It is still uncertain how the paste technology affects the long-term environmental stability from a geochemical point of view. Concerns regarding the stability of paste with high sulphide content are still relevant. Studies performed indicate that sulphide oxidation occurs within cemented paste as well as on the surface of non-cemented paste and cracks formed on the surfaces could induce oxidation. For cemented paste, metals released by sulphide oxidation might be sequestered due to high pH induced by the alkaline additives, but anion such as Se has been shown to be mobilized. The leachate has been shown to be near-neutral initially, but the neutrality decreases with time and probably metals sequestered in the matrix will also be released. Again, it should be noted that no long term study was performed on leaching of paste, cemented or uncemented. The longest leaching study was performed for one year. Arsenic has been proven to be retained in Ca-arsenates in cemented paste, but the long term stability of these precipitates is relatively unknown. Expanded secondary phases e.g. gypsum and ettringite have been observed to form when there is sulphate in the process or drainage of water. These phases could crack the paste, but, on the other hand, can also fill former cracks when deposited in layers. The effects of the formation of these phases are relatively uncertain in a long-term perspective. Presence of different elements such as ammonium, sulphates and metals in the water has been shown to negatively affect the curing process and therefore water is suggested to be treated before use. The presence of carbon dioxide during the paste formation could also affect the curing process, but could sequester metals in carbonate phases.Geotechnical and rheological properties of paste is well defined and documented. Several case studies have been found in literature providing valuable information about the details of the works being carried out. However, a difficulty has been noted during the investigation of the effects of cold climate conditions when current practice is applied in the colder parts of the world. It is not certain how some specific and vital parameters are going to be affected by cold temperatures. Parameters such as deposition slopes and deposition scheme, strength development of the paste are expected to be responsive to cold climate conditions. There are predictions about which properties are going to be affected in what way, but there is also a need to establish a scientific base for discussion. These have been highlighted as research needs and information gaps at the end of the report.

  • 41.
    Alakangas, Lena
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Andersson, Elin
    Vectura Consulting AB.
    Mueller, Seth
    Boliden Mineral AB.
    Neutralization/prevention of acid rock drainage using mixtures of alkaline by-products and sulfidic mine wastes2013In: Environmental science and pollution research international, ISSN 0944-1344, E-ISSN 1614-7499, Vol. 20, no 11, p. 7907-7916Article in journal (Refereed)
    Abstract [en]

    Backfilling of open pit with sulfidic waste rock followed by inundation is a common method for reducing sulfide oxidation after mine closure. This approach can be complemented by mixing the waste rock with alkaline materials from pulp and steel mills to increase the system’s neutralization potential. Leachates from 1 m3 tanks containing sulfide-rich (ca.30 wt %) waste rock formed under dry and water saturated conditions under laboratory conditions were characterized and compared to those formed from mixtures. The waste rock leachate produced an acidic leachate (pH < 2) with high concentrations of As (65 mg/L), Cu (6 mg/L), and Zn (150 mg/L) after 258 days. The leachate from water-saturated waste rock had lower concentrations of As and Cu (<2 μg/L), Pb and Zn (20 μg/L and 5 mg/L), respectively, and its pH was around 6. Crushed (<6 mm) waste rock mixed with different fractions (1–5 wt %) of green liquid dregs, fly ash, mesa lime, and argon oxygen decarburization (AOD) slag was leached on a small scale for 65 day, and showed near-neutral pH values, except for mixtures of waste rock with AOD slag and fly ash (5 % w/w) which were more basic (pH > 9). The decrease of elemental concentration in the leachate was most pronounced for Pb and Zn, while Al and S were relatively high. Overall, the results obtained were promising and suggest that alkaline by-products could be useful additives for minimizing ARD formation

  • 42.
    Villain, Lucile
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Alakangas, Lena
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Öhlander, Björn
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    The effects of backfilling and sealing the waste rock on water quality at the Kimheden open-pit mine, northern Sweden2013In: Journal of Geochemical Exploration, ISSN 0375-6742, E-ISSN 1879-1689, Vol. 134, p. 99-110Article in journal (Refereed)
    Abstract [en]

    Evaluating the water quality at reclaimed mines affected by acid mine drainage is an essential step in assessing and improving the performance of mitigation techniques. At the Kimheden copper mine in northern Sweden, reclamation involved the progressive backfilling of waste rock into the two small open pits and, in 1996, the application of a till dry cover that included a sealing layer. The data from both the long-term water quality monitoring by the mining company and the repeated sampling of the surface water and groundwater in 2009 and 2010 were used to assess the success of the reclamation in mitigating the acid mine drainage production from the mine waste. A substantial decrease in the concentrations of copper, zinc and sulphate ions by 95%, 81% and 81%, respectively followed by a rapid stabilisation of element concentrations was observed at the outlet of the receiving stream since early reclamation times. This trend initially suggested successful results for the reclamation, though another explanation for the diminution of contaminant release through depletion of the limited sulphidic source could not be neglected. However, in spite of the decrease, post-reclamation metal concentrations in the stream are still not satisfactory for the discharge of the mine drainage into the natural environment, indicating that the mitigation measures were insufficient. Seepage from one of the pits in 2009 had dissolved copper, aluminium and zinc concentrations of 1.6 mg/L, 4.4 mg/L and 0.45 mg/L, respectively and a pH of 3.0. Relatively high dissolved oxygen concentrations in the groundwater of the backfill in 2009 and 2010 (> 2 mg/L) suggest that the mixed outcome of the mitigation actions is due to on-going oxidation in the backfilled waste rock despite the dry cover. Moreover, stream discharge and dissolved sulphate and magnesium used as natural tracers in the drainage showed that water management in the form of ditches is not appropriate. In particular, due to poor sealing of the ditches, whilst a measurable part of the contaminated drainage in the collecting ditch is leaking to groundwater and dispersing in the surrounding natural areas, the water discharged to a treatment pond at the outlet of the stream is mostly uncontaminated background water.

  • 43.
    Nason, Peter
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Alakangas, Lena
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Öhlander, Björn
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Using sewage sludge as a sealing layer to remediate sulphidic mine tailings: a pilot-scale experiment, northern Sweden2013In: Environmental Earth Sciences, ISSN 1866-6280, E-ISSN 1866-6299, Vol. 70, no 7, p. 3093-3105Article in journal (Refereed)
    Abstract [en]

    At the Kristineberg mine, northern Sweden, sulphidic mine tailings were remediated in an 8-year pilot-scale experiment using sewage sludge to evaluate its applicability as a sealing layer in a composite dry cover. Sediment, leachate water, and pore gas geochemistry were collected in the aim of determining if the sludge was an effective barrier material to mitigate acid rock drainage (ARD) formation. The sludge was an effective barrier to oxygen influx as it formed both a physical obstruction and functioned as an organic reactive barrier to prevent oxygen to the underlying tailings. Sulphide oxidation and consequential ARD formation did not occur. Sludge-borne trace elements accumulated in a reductive, alkaline environment in the underlying tailings, resulting in an effluent drainage geochemistry of Cd, Cu, Pb and Zn below 10 μg/L, high alkalinity (810 mg/L) and low sulphate (38 mg/L). In contrast, the uncovered reference tailings received a 0.35-m deep oxidation front and typical ARD, with dissolved concentrations of Cd, Zn and sulphate, 20.8 μg/L, 16,100 μg/L and 1,390 mg/L, respectively. Organic matter degradation in the sludge may be a limiting factor to the function of the sealing layer over time as 85 % loss of the organic fraction occurred over the 8-year experimental period due to aerobic and anaerobic degradation. Though the cover may function in the short to medium term (100 years), it is unlikely to meet the demands of a long-term remedial solution

  • 44.
    Öhlander, Björn
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Forsberg, Jerry
    Österlund, Helene
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Ingri, Johan
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Ecke, Frauke
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Alakangas, Lena
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Fractionation of trace metals in a contaminated freshwater stream using membrane filtration, ultrafiltration, DGT and transplanted aquatic moss2012In: Geochemistry: Exploration, Environment, Analysis, ISSN 1467-7873, E-ISSN 2041-4943, Vol. 12, no 4, p. 303-312Article in journal (Refereed)
    Abstract [en]

    Four metal speciation and fractionation techniques – DGT (diffusive gradients in thin films), 1-kDa ultrafiltration, 0.22-µm membrane filtration and aquatic moss – were simultaneously applied to a small, contaminated freshwater stream in northern Sweden to investigate differences and similarities between the methods regarding trace metal speciation and their dependence on geochemical water properties. The investigated metals comprise Al, Cd, Co, Cu, Fe, Mn, Ni, and Zn. The normal DGT devices with Chelex cation exchanger were used. Shoots from the aquatic moss Fontinalis antipyretica L ex Hedw. were collected in a non-polluted brook and transplanted to the sampling site for exposure. It was evident that 0.22-µm membrane filtration, 1-kDa ultrafiltration and DGT generally measured different metal fractions where

  • 45.
    Öhlander, Björn
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Chatwin, Terrence
    Alakangas, Lena
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Management of sulfide-bearing waste: a challenge for the mining industry2012In: Minerals, ISSN 2075-163X, E-ISSN 2075-163X, Vol. 2, no 1, p. 1-10Article in journal (Refereed)
    Abstract [en]

    Oxidation of iron sulfides in waste rock dumps and tailings deposits may result in formation of acid rock drainage (ARD), which often is a challenging problem at mine sites. Therefore, integrating an ARD management plan into the actual mine operations in the early phases of exploration, continuing through the mine life until final closure might be successful and decrease the environmental impact. A thorough characterization of ore and waste should be performed at an early stage. A detailed knowledge of mineralogical composition, chemical composition and physical properties such as grain size, porosity and hydraulic conductivity of the different waste types is necessary for reliable predictions of ARD formation and efficiency of mitigation measures. Different approaches to prevent and mitigate ARD are discussed. Another key element of successfully planning to prevent ARD and to close a mining operation sustainably is to engage the mine stakeholders (regulators, community and government leaders, non-governmental organization (NGOs) and lenders) in helping develop and implement the ARD management plan.

  • 46.
    Öhlander, Björn
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Alakangas, Lena
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Perez, Nathalie
    Project: Using MicroBes for the Regulation of heavy metaL mobiLity at ecosystem and landscape scAle: an integrative approach for soil remediation by geobiological processes2012Other (Other (popular science, discussion, etc.))
  • 47.
    Alakangas, Lena
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Lundberg, Angela
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Nason, Peter
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Simulation of pyrite oxidation in fresh mine tailings under near-neutral conditions2012In: Journal of Environmental Monitoring, ISSN 1464-0325, E-ISSN 1464-0333, Vol. 14, no 8, p. 2245-2253Article in journal (Refereed)
    Abstract [en]

    Sulphidic residual products from ore processing may produce acid rock drainage, when exposed to oxygen and water. Predictions of the magnitude of ARD and sulphide oxidation rates are of great importance in mine planning because they can be used to minimize or eliminate ARD and the associated economic and environmental costs. To address the lack of field data of sulphide oxidation rate in fresh sulphide-rich tailings under near-neutral conditions, determination and simulation of the rate was performed in pilot-scale at Kristineberg, northern Sweden. The quality of the drainage water was monitored, along with oxygen and carbon dioxide concentrations. The chemical composition of the solid tailings was also determined. The field data were compared to predictions from simulations of pyrite oxidation using a 1-D numerical model. The simulations' estimates of the amount of Fe and S released over a seven year period (52 kg and 178 kg, respectively) were in reasonably good agreement with those obtained by analysing the tailings (34 kg and 155 kg, respectively). The discrepancy is probably due to the formation of secondary precipitates such as iron hydroxides and gypsum; which are not accounted for in the model. The observed mass transport of Fe and S (0.05 and 1.0 kg per year, respectively) was much lower than expected on the basis of the simulations and the core data. Neutralization reactions involving carbonates in the tailings result in a near-neutral pH at all depths except at the oxidation front (pH < 5), indicating that the dissolution of carbonates was too slow for the acid to be neutralized, which instead neutralized deeper down in the tailings. This was also indicated by the reduced abundance of solid Ca at greater depths and the high levels of carbon dioxide both of which are consistent with the dissolution of carbonates. It could be concluded that the near-neutral pH in the tailings has no decreasing effect on the rate of sulphide oxidation, but does reduce the concentrations of dissolved elements in the drainage water due to the formation of secondary minerals. This means that sulphide oxidation rates may be underestimated if determined from drainage alone.

  • 48.
    Nason, Peter
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Alakangas, Lena
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Öhlander, Björn
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Assessing the impact of sewage sludge on a formally remediated tailings impoundment in relation to the transport of metals in groundwater2011In: Mine Water - managing the Challenges: 11th Congress of the International Mine Water Association / [ed] Thomas R. Rüde; Antje Freund; Christian Wolkersdorfer, Aachen, Germany: RWTH Aachen University, Institute of Hydrogeology , 2011, p. 429-434Conference paper (Refereed)
    Abstract [en]

    In 2009 sewage sludge was applied to an already successfully remediated saturated and dry covered sulphide tailings impoundment in northern Sweden as a vegetation substrate. The aim of this study was to identify the dispersion, magnitude and duration of sludge-borne constituents released. Readily leachable sludge-borne constituents (DOC, Fe, Co, Cr, Ni, Pb and Zn) created a contamination plume which affected the impoundment groundwater within the first year of application. The majority of the plume originated from the water-saturated area of the impoundment that was only covered with a 10% surface area of sludge. The dry-composite covered area of the impoundment, which contained a 70% sludge cover, did not contribute to the contamination plume due to the efficiency of the cover at reducing water infiltration and contamination dispersal. The constituents were transported along the dominant groundwater flow direction, underneath the dry covered area of the impoundment, to the effluent of the impoundment groundwater system due to inflowing uncontaminated groundwater from an adjacent till slope. All metal and DOC concentrations in the impoundment groundwater returned to pre-sludge application concentrations within two years, due to successful plant establishment on the sludge.

  • 49.
    Rodríguez, Nathalie Pérez
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Nason, Peter
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Alakangas, Lena
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Öhlander, Björn
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Copper and iron isotopes in mine tailings and their relationship to weathering processes2011Conference paper (Other academic)
  • 50.
    Rodríguez, Nathalie Pérez
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Nason, Peter
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Alakangas, Lena
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Öhlander, Björn
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Copper isotope fractionation in mine tailings in northern Sweden.2011Conference paper (Refereed)
12 1 - 50 of 69
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